1. A clinical trial was conducted with flurbiprofen 100 mg three times a day by mouth in rheumatoid arthritis to determine variability in response. 2. Forty patients entered the study, but only 32 completed it. Patients were treated with flurbiprofen on two occasions at a month's interval, each being preceded by a 3 day wash out period. Pain relief and a Ritchie articular index of joint tenderness was assessed at the beginning and end of each treatment period. 3. Flurbiprofen produced significant improvement in both pain relief and articular tenderness. No significant differences were observed between the two trial periods in the mean of these outcome measures. 4. No evidence was found to support the concept of responders and non-responders.